Tungsten crucible is one of metal tungsten products, mainly divided into sintering molding (applied to powder metallurgy technology), stamping molding, spinning type. The use of tungsten rod turning processing molding (generally smaller size), welding molding a variety of, using [2] pure tungsten plate, tungsten sheet and pure tungsten rod by the corresponding process. Tungsten crucible can be used in vacuum inert gas below 2600 degrees. Tungsten has high melting and boiling points, good high temperature strength, wear and corrosion resistance, large thermal conductivity, small coefficient of thermal expansion and good hardenability. Tungsten crucible is widely used in rare earth smelting, quartz glass, electronic spraying, crystal growth and other industries.
Chemical properties of tungsten crucible.
Tungsten is a rare high melting point metal, which can improve the high temperature hardness of steel, and belongs to the VIB group of the sixth period (**long period) in the periodic table of elements. Tungsten is a silver-white metal with a steel-like appearance. Tungsten has a high melting point, a very low vapor pressure, and a small evaporation rate. The chemical property of tungsten is very stable, it does not react with air and water at room temperature, when not heated, any concentration of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid and aqua regia do not have any effect on tungsten, when the temperature rises to 80 ° – 100 ° C, in addition to hydrofluoric acid in the above acids, the other acids on tungsten have a weak effect. At room temperature, tungsten can be quickly dissolved in the mixture of hydrofluoric acid and concentrated nitric acid, but not in alkaline solution. In the presence of air, molten alkali can oxidize tungsten into tungstate, and in the presence of oxidizing agents (NaNO3, NaNO2, KClO3, PbO2), the reaction to produce tungstate is more violent. It can chemically combine with chlorine, bromine, iodine, carbon, nitrogen and sulfur at high temperature, but not with hydrogen.
